Patent GB-806213-A (GB)
Title: Method and apparatus for slitting tires
IPC: B29D30/68
Filed: 1956-08-20
Abstract: 806,213. Tyre making apparatus. GOODYEAR TIRE & RUBBER CO. Aug. 20,1956 [Dec. 22, 1955], No. 25347/56. Class 144 (1). [Also in Groups VIII and XXII] Apparatus for slitting tyre treads comprises means for holding a tyre in freely rotatable position, a rotatable cutter carriage having at least one helical cutter adapted to pass transversely across the tyre tread, and means for moving the tyre-holding means towards and away from the cutter or cutters in a plane containing the axis of rotation of the carriage. The tyre-tread may be slit partly or wholly across its width. As shown in Fig. 1, the apparatus comprises a continuously rotatable knife carriage 1 and tyre chucking and supporting units 2, 3, 4 to permit three tyre treads to be slit simultaneously. A plurality of arcuate knife holders 19, 20 are secured to the carriage and hold therebetween a plurality of helical knives 21. The respective leading and trailing edges 24, 26, Fig. 6, of adjacent knives are spaced apart by means of a replaceable spacer member 29 to a distance equal to the desired spacing between slits 27 to be cut on the tyre 28. As the leading edge 24 of one of the knives completes a cut, it will follow through the slit and displace the tyre tread a distance equal to the spacing between the trailing and leading edges of the knives. A nozzle 32 is provided at each side of the knife carriage for spraying water or other suitable cutter lubricant and cooling fluid. Associated with each of the units 2, 3, 4 is a tyre-tread support comprising a set of freely rotatable rollers 33, 34, Fig. 7, mounted at each side of the rotatable knives 21. The sets of rollers can be raised or lowered by rotating a ring 44 threadedly engaging a shaft 38 so as to increase or decrease the depth of the slits 27. Each unit 2, 3, 4 comprises a stand 46, Fig. 3, within which is journalled a vertical shaft 49 to the upper end of which is secured a collar 50 having a radial lug 51 which is secured to the lower end of the shaft 49 by means of a vertical arm 52. The arm 52 bears against one of two pins 53, 54 (not shown), so as to limit the rotation of the shaft 49. When the arm 52 bears against pin 53, the tyre is disposed over the knives, as shown in Fig. 19. When the arm 52 bears against pin 54 (not shown), the tyre is in a loading position, Fig. 18. Each of the units is rotated into its slitting and loading positions by means of a lever 55, Fig. 11, and means are provided for locking the lever in each of its two positions. When the lever is locked. in the slitting position of a unit, a microswitch 60 secured to the stand 46 is closed. The collar 50 is provided with a bracket 62, Fig. 11, which is inclined at an angle corresponding to the angle of the plane of the tyre 28 relative to a vertical plane during the slitting operation. Secured to the bracket 62 are a pair of aligned rings 65 having bearings 66 which respectively supports stub shafts 67 68 about which is pivotable a housing 69 having rotatably mounted therewithin a main shaft 73 which is rotatable about its own axis by means of a pneumatically-operated torque unit 77. The forward end of the shaft 73 is secured to a housing 84 which supports a tyre chuck 85 comprising movable and fixed heads 89, 94 respectively supported on struts 88, 95. When the head 89 is moved by means of a pneumatic cylinder 92 to close the chuck, a microswitch 96 secured to the housing 84 is closed. The outer ends of the struts 88, 95 are provided with journalled rings 98, 99 respectively which rotatably support stub shafts 100, 101, Fig. 12, secured respectively to circular plates 102, 103 having telescoping cylindrical flanges 104, 105, each of which is provided with an annular tyre bead flange 106, 107. The stub shaft 100 is provided with a bore 109 connecting with an axial bore 110 in the flange 104 which terminates in an opening 111 through which air supplied from a line 113 may be admitted to inflate the tyre. The heads 89, 94 of the chuck 85 may be locked in the closed position by means of a plurality of lugs 114 which are adapted to be expanded to engage the flange 115 of a cylindrical member 116 secured to the plate 102 by means of pivoted links 117 secured to a tapered cylindrical member 120 fixed to a rod 123 which is reciprocable axially by means of a pneumatic piston and cylinder device 124, 125. A microswitch 135 is closed when the chuck is locked. The outer end 139, Fig. 11, of the main shaft 73 is operatively connected to the piston-rod 141 of cylinder 142. Air under pressure supplied through the line 144 causes the main shaft 73 and the tyre supporting unit to be pivoted about the axes of the stub shafts 67, 68 to lower the tyre on to the tread supporting rolls 33, 34. The stub shaft 68 is provided with arms 147, 148, Fig. 3, which respectively closes microswitches 149, 150 when the main shaft 73 is rotated about the stub shafts 67, 68. Switch 149 is closed when the tyre is in its fully raised position while switch 150 is closed when the tyre is in its fully lowered position. A diaphragm lift 151 is provided with an adjustable rod 153 adapted, when the tyre is in its fully lowered position, to contact one of two rods 154, 155 projecting from opposite sides of the housing 84. The shaft 79 of the torque unit 77 is provided with a collar 164 having a radially extending lug which is adapted to contact the actuating arms of microswitches 168, 169 which control the operation of chuck braking mechanism. Secured to the chuck head 94 is a notched cam wheel 170, Figs. 12 and 13, engaged by a spring-influenced roller 172 supported on a carriage 173 reciprocable within a guide 174. A single-acting cylinder 176 is actuated when it is desired to brake the freely rotatable chuck. The carriage 173 is also provided with cams 177, 178 which are adapted to engage rollers 179, 180, respectively. A limit switch 182 actuated by cam 178 contacting the roller 180 provides the impulse required for actuating the mechanism to lift the tyre from the knives after the cutting is complete, and lock the tyre against rotation whenever it is lifted off the knives. A limit switch 181 actuated by the cam 177 contacting the roller 179 provides the impulse required for slowing the speed of rotation of the knife carriage just before the tyre is removed from the knives. A bracket 183, Fig. 3, secured to the torque unit 77 supports a control panel 184 having a plurality of control push-buttons mounted thereon. The push-buttons and the various microswitches referred to are included in an electric circuit, Fig. 23 (not shown). Operation.-With the tyre-holding and supporting unit in the loading position, Fig. 18, a tyre is placed on the fixed chuck head 94. Air is caused to enter the cylinder 92 to close the chuck 85 and thereby close the microswitch 96. Air is then allowed to enter the cylinder 125 to lock the chuck and thereby close tho microswitch 135. Air is permitted to pass through line 113 to inflate the tyre. The tyre supporting unit is then rotated clockwise as shown in Fig. 18 by means of the lever 55 until the arm 52 engages the pin 54 (not shown). The tyresupporting unit is locked in the slitting position, as shown in Fig. 19, and the microswitch 60 closed. Air is admitted to the cylinder 142 and the diaphragm 151 and cylinder 176 exhausted. The main shaft 73 is thereby rotated about the stub shafts 67, 68 and the tyre lowered into engagement with the knives. The exhausting of the cylinder 176 permits the tyre to be freely rotated and the microswitch 150 to be closed. After one shoulder of the tyre has been slit and the tyre rotated round its axis for 360 degrees, the limit switch 182 is closed by the roller 180 thereby admitting air to the cylinder 182, diaphragm 151 and cylinder 176 which respectively pivot the main shaft 73 to lift the tyre off the knives and lock the tyre against rotation. When the tyre has reached its fully raised position, the microswitch 149 is closed causing the torque unit 77 and the main shaft to be rotated counterclockwise for 180 degrees to invert the tyre. When the tyre has been inverted, the microswitch 168 is closed. This causes air to be admitted to the cylinder 142 and the diaphragm 151 and cylinder 176 to be exhausted. When the tyre is in its fully lowered position, the microswitch 150 is closed. The tyre is now in cutting position, the microswitch 150 is closed. The tyre is now in cutting position on the knives, as shown in Fig. 22. When the second side of the tyre has been completely slit, the roller 180 closes the microswitch 182, thereby fully raising the tyre and locking it against rotation. The microswitch 149 is closed to admit air to the torque unit 77 which revolves the tyre from the 180 degree position to the starting position, as shown in Fig. 19. When the tyre reaches the starting position, the microswitch 169 is closed to cause the tyre to be deflated. The lever 55 is operated to swing the unit into loading position, Fig. 18. The chuck is then unlocked and opened so that the slitted tyre may be removed. U.S.A. Specification 1,971,651 is referred to.